Dental implant abutment

ABSTRACT

A process for the manufacture of a dental implant restoration system including an abutment for attaching a dental prosthesis within a patient&#39;s mouth. The abutment is a single unit structure fabricated of a ceramic material, multicolored throughout to match the color of the dental prosthesis, the surrounding dentition and the surrounding gingival tissue.

REFERENCE TO RELATED APPLICATIONS

This application claims priority to and is a continuation application ofU.S. application Ser. No. 13/736,496, filed Jan. 8, 2013, which claimspriority to and is a continuation application of U.S. application Ser.No. 12/027,657, filed Feb. 7, 2008, now U.S. Pat. No. 8,371,851, whichclaims priority to and is a continuation-in-part application of U.S.application Ser. No. 10/799,513, filed Mar. 12, 2004, all of which arehereby incorporated by reference.

BACKGROUND

The present invention relates generally to restorative dentistry. Morespecifically, the invention relates to an implant abutment for dentalrestorations.

Restorative dentistry has made significant advances in the use of dentalimplants to support dental restorations intended to permanently replacenatural teeth. Dental implants provide an alternative to removabledentures, fixed partial dentures, and single-tooth restorations.

In a jawbone anchored dental restoration, an implant of known design issurgically implanted into a patient's jawbone, leaving a gingivalsurface exposed. A support post, commonly referred to as an abutment, isthen firmly fixed to the exposed surface of the implant. A dentalprosthesis is secured to the abutment by means of a screw extendingthrough a bore in the prosthesis and into a threaded bore in theabutment (screw retained) or via conventional cementation techniques(cement retained).

As described, for example, in U.S. Pat. No. 4,988,298 to Lazzara et al.,the entire content of which is incorporated herein by reference, and asshown in FIG. 1, a dental implant restoration system 10 generallyincludes a dental implant 14, a support post or abutment 16, and aprosthesis 12. The implant is typically made from a biocompatiblematerial such as titanium or titanium alloy, and is embedded into thejawbone leaving a gingival surface 22 flush or nearly flush with thegingival surface A-A of the jawbone. This gingival end includes aninternally-threaded recess 24 and a multi-sided male projection forabutting with the abutment 16. The abutment 16 is securely attached tothe lower or gingival end of the prosthesis 12 and functions to providea rigid interconnection between the implant 14 and the prosthesis 12.

A passageway extends through the abutment 16 and provides a recess atthe transgingival portion for engaging the projection of the implant. Ascrew 26 abuts against a shoulder 28 of the abutment and engages thethreaded recess 24 of the implant to force a precision formed abutmentsurface 29 into seated contact with the gingival surface of the implant.The prosthesis 12 is fabricated around the upper portion of the abutmentand may be connected to the abutment via screw 26 or cement. Theprosthesis is colored to match the surrounding dentition.

Typically, the abutment is made of metal, such as titanium, and theprosthesis is fabricated from ceramic, a ceramic-based material such asporcelain, or a polymeric resin material. An entirely metallic abutmenthowever, can be visible through the prosthesis, resulting in a dark,central rod-like shadow, particularly when exposed to bright light,which makes the prosthesis somewhat unattractive since it isdistinguishable from a natural tooth. Various methods for preventing ormasking the appearance of the shadow are known in the art.

One attempt to solve the attractiveness problem involves making asupport post entirely of tooth-colored ceramic material. This approachallows direct surface bonding by interaction of a porcelain copingand/or prosthesis to the support post, resulting in a secure and almostseamless bond between the prosthesis and support post. While presentingan attractive alternative to the use of a titanium support post, theproposed solution presents a number of problems.

Ceramic materials generally have a much greater hardness than titanium.When an all-ceramic support post is used, inevitable rocking of thesupport post due to, for example, chewing, causes a high stressinteraction between the metal implant and the ceramic material of thepost. Since a ceramic support post is of greater hardness than atitanium implant, it can and does cause damage to the implant. Ifsufficient damage is caused, eventual surgical intervention is requiredto remove and replace the titanium implant. In addition, ceramicmaterial is typically not radiopaque, and when using conventional x-rayimaging to examine the juncture between the abutment and the titaniumimplant, the interface between the two elements is not readily viewableand adequate examination cannot be conducted. Moreover, fracture of theall-ceramic post is also a consideration.

Recognizing the benefits of a metallic support, U.S. Pat. No. 5,685,714to Beaty et al. describes an abutment having two distinct sections. Asseen in FIG. 2, abutment 12 includes an inner section, or core 36, madefrom titanium or a titanium alloy and an outer section, or cuff 34, madefrom ceramic, typically aluminum oxide. The metallic core 36 providesthe necessary strength to the abutment and provides a framework forconnecting prosthesis 38 to implant 40. The ceramic cuff 34 preferablysurrounds the entire exterior surface of the core 36, and shields theshadow of the metallic core 36 through the prosthesis 38. PureForm™(Centerpulse Dental Inc., Carlsbad, Calif.), for example, is atooth-shaped abutment composed of a titanium core and a ceramic cuffmade of an alumina/zirconia blend. Screw-retained alumina orzirconia/alumina based abutments are available under the trademarksBio-Cera™ (Bio-Lok International, Inc., Deerfield Beach, Fla.),CerAdapt™ (Nobel Biocare™ AB, Goteborg, SE) and ZiReal™ Post (ImplantInnovations, Inc., Wilmington, Del.).

U.S. Pat. No. 6,497,573 to Wagner et al. describes a three part dentalabutment that includes a shield between a metallic core and a polymericcuff. The shield is preferably formed of an opaque material, such as amixture of several mono and dimethacrylates, and may include variouspigments to provide a variety of colors to best shield or mask anygrayish or metallic color of the core.

U.S. Pat. No. 7,179,089 is directed to a two-part abutment having anupper section fabricated of a metal, zirconia or alumina cylinder and ashoulder attached to the cylinder and fabricated of a hybrid ceramicmaterial, whereby a pigment may be added to the hybrid ceramic materialto match the color of the patient's gum tissue.

Each of the aforementioned devices however, have certain drawbacks. Thethree part system is inherently more costly, both in time and materials.The two-part system of U.S. Pat. No. 7,179,089 requires the attachmentof the cylinder to the shoulder component. Moreover, the two partsystems, while effectively masking the shadow of the metallic core,result in the requirement for additional time and expertise in thefabrication of the prosthesis. When utilizing an entirely metallicabutment, the technician simply acknowledged the resulting appearance ofthe shadow and fabricated a prosthesis that matched the surroundingdentition. With the addition of a cuff component, however, the color ofthe cuff and the color of the prosthesis combine to create the color ofthe final restoration, and the technician must therefore take the colorof the abutment into consideration when fabricating the prosthesis.

This is particularly important when the prosthesis is fabricated ofceramic. Since most ceramic restorations have inherent translucency, itis incumbent that the abutment be shaded so that it complements thedesired shade of the restoration. This process is similar to determiningthe shade of a natural tooth prior to the fabrication of an all ceramiccrown. In that case, it is recognized that the underlying natural toothor “stump” will influence the shade of the final restoration.

U.S. Pat. Nos. 6,231,342 and 5,989,029 are directed to customizedabutments and are hereby incorporated by reference. The abutments arecustomized by taking a series of measurements at the tooth site andfabricating an abutment based on the measurements. Although theabutments, are customized single-unit structures, there are no color andshade considerations.

Conventional abutments, such as PureForm™ Ceramic Coping (CenterpulseDental Inc., Carlsbad, Calif.), Bio-Cera™ (Bio-Lock International, Inc.,Deerfield Beach, Fla.), CerAdapt™ (Nobel Biocare™ AB, Goteborg, SE) andZiReal™ (Implant Innovations, Inc., Wilmington, Del.), are typicallyavailable in one standard color chosen by the manufacturer, regardlessof the material they are made from. Thus, an “exact match” between theabutment and prosthesis is not achieved. CerAdapt™ abutments forexample, are available in Vita-Shade™ A-3 (Vita Shade™ Guide, Vident,Brea, Calif.).

SUMMARY OF THE INVENTION

In one embodiment, the present invention provides an aesthetic implantabutment for attaching a restorative dental prosthesis within apatient's mouth. In accordance with the invention, the implant abutmentincludes a core and a cuff surrounding the core, wherein the cuff iscolored to match the color of the prosthesis.

In various embodiments, the core is fabricated from metal, such astitanium or a titanium alloy, and the cuff and prosthesis are fabricatedfrom a ceramic or polymeric material. In a preferred embodiment, boththe cuff and prosthesis are formed of ceramic.

The invention further provides a dental implant restoration system thatincludes an implant, a dental abutment having a core and a cuffsurrounding the core fixed to the implant, and a dental prosthesis fixedto the abutment, wherein the abutment cuff is colored to match the colorof the prosthesis.

The invention also provides a method of fabricating a dental implantrestoration that includes, fixing an implant within a patient's mouth;fixing a dental abutment having a core and a cuff surrounding the core,to the implant; and fixing a dental prosthesis to the abutment, whereinthe abutment cuff is colored to match the color of the prosthesis.

In yet another embodiment, a single unit abutment is fabricated of aceramic material, shaded to match the color of the dental prosthesis,and/or the surrounding dentition and the surrounding gingival tissue.The abutment is anatomically shaped and shaded to match the near netshape and shade of the prosthesis that is attached thereto. As theabutment gets closer to the net shape and becomes more naturally shaded,it obviates the need for a restoration on top and becomes therestoration itself. Additionally, the abutment is shaded to match thecolor of the surrounding dentition and gingival tissue.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a partial cross-sectional view of a prior art dental abutmentfixed within a dental implant restoration system.

FIG. 2 is a partial cross-sectional view of a prior art dental abutmentfixed within a dental implant restoration system.

FIG. 3 is a partial cross-sectional view of a dental restorative systemaccording to one embodiment of the present invention.

FIG. 4 is a perspective view of the facial side of the abutmentaccording to an embodiment of the present invention.

FIG. 5 is a perspective view of the lateral side of the abutment of FIG.4.

FIG. 6 is a perspective view of the top side of the abutment of FIG. 4.

FIG. 7 is a partial cross-sectional view of a dental implant systemaccording to another embodiment of the present invention.

FIG. 8 is a perspective view of a dental implant system according toanother embodiment of the present invention.

FIG. 9 is a perspective view of the facial side of the abutment in theimplant system of FIG. 8.

FIG. 10 is a perspective view of the facial side of the abutment in theimplant system of FIG. 8.

FIG. 11 is a perspective view of a bore in the abutment in FIGS. 9 and10.

FIG. 12 is a perspective view of an alternative bore disposed in theabutment in FIGS. 9 and 10.

FIG. 13 is a close-up cut-away view of the top of the implant shown inFIG. 8.

FIG. 14 is a top plan view of the implant in FIG. 13.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 3 shows a dental restorative system 100 that includes a prosthesis102, an abutment 104, and an implant 106. The abutment and prosthesisare attached together and connected to the implant as illustrated.

Implant 106 has a coronal or gingival end with a threaded bore 110 and amale engaging feature 112 extending upwardly. The coronal end extendsdownwardly along a cylindrical body to a distal end. The male engagingfeature 112 connects to the abutment and may be a plurality of upwardlyextending tines, a polygon, or other type feature known to those skilledin the art. Alternatively, the implant may have female engaging featuresthat correspond with male projections on the abutment core. The implantmay be any one of various implants known in the art, such as thosemanufactured by Sulzer Calcitek Inc. (Carlsbad, Calif.).

Abutment 104 has two different and distinct sections preferably formedfrom two different materials. Core section 120 has a cylindricalconfiguration and extends from a top portion to a bottom portion. Apassageway 126 extends centrally through the core. The bottom portionabuts against the coronal end of implant 106. Abutment 104 may beprovided with a female engaging feature 128 that engages with the maleengaging feature 112 to provide an anti-rotational connection betweenthe abutment and implant. The engaging features would have matchingconfigurations to provide the noted anti-rotational connection. Numerousconfigurations of engaging features known to those skilled in the art(such as Spline® tines, octagons, and other polygons) may be used.

Core 120 typically includes a shoulder 130 located along the interior ofthe passageway 126 at the top portion. A corresponding ledge 132 isformed along the exterior surface adjacent shoulder 130. Preferably, thecore is made from a biocompatible metal, such as titanium or its alloys.The metallic core provides strength to the abutment and a framework forconnecting the prosthesis to the implant.

An abutment cuff section 140 connects to the exterior surface of thecore 120 and, preferably, surrounds the entire exterior surface. Thecuff has a somewhat cylindrical configuration and extends from an upperportion to a lower portion. The cuff can be shaped around the core tohave various configurations, such as a cylindrical or ellipticalconfiguration or an anatomical shape that resembles the cross section ofa natural tooth.

As shown in FIG. 3, the cuff 140 tapers outwardly and upwardly away fromthe coronal end of the implant 106 and forms a frusto-conical shape.This tapering continues to a ledge 146 and then transitions to taperinwardly at the upper portion of the cuff 140. A shoulder 148 is locatedalong the inner surface. This shoulder 148 fits with the mating ledge132 on the exterior of the core.

The prosthesis 102 is shaped as a natural tooth and includes apassageway 150 that aligns with the passageway 126 of the abutment. Ascrew 152 passes into these passageways until a head 154 of the screwabuts against the top portion of the core. As shown, the lower portionof the head includes a taper 156 that abuts against the shoulder 130along the interior of the core. The screw includes a shank 158 extendingfrom the head. This shank has a threaded portion 160 that fits into thecoronal end of the implant to engage corresponding threads in threadedbore 110. The screw holds the abutment and attached prosthesis to theimplant. The head 154 also includes a recess 162. The recess may beprovided to engage a tool (not shown) for tightening and loosening thescrew or provided to threadably engage another screw (not shown) tosecure the prosthesis.

In accordance with one embodiment of the invention, the color of theabutment cuff 140 matches the color of the prosthesis 102. While thecuff 140 and the prosthesis 102 are preferably made from a ceramicmaterial, such as the zirconia/alumina composite described in U.S. Pat.No. 6,380,113 to Kim et al., various polymers and polymer combinationssuch as acrylic polymers; fiber, glass, silica, and alumina reinforcedpolymers; thermosetting and photosensitive polymers; vinylesters; andepoxy type materials, may also be used. Suitable polymers includeSculpture™ or FibreKor™ of Jeneric/Pentron, Inc. (Wallingford, Conn.)and Targis™ or Vectris™ of Ivoclar Vivadent, Inc. (Schaan, LI).

In the context of the present invention, “matching” the color of theabutment cuff to the color of the prosthesis means choosing a color forthe abutment cuff that is most similar to the color of the prosthesis.Generally, a restoration is fabricated in more than one color shade,typically with a darker shade at the gingival surface and a brightershade at the top. However, the abutment color is selected to match theoverall color of the prosthesis, especially at the interface of theabutment 140 and the restoration 104.

Several methods are known in the art for determining the color of adental restoration. Most commonly used is a dental shade guide, whichgenerally has a base supporting a plurality of tabs or other indicia,each of which corresponds to a different color. The colors of thetabs/indicia represent a range of standard tooth colors. U.S. Pat. No.6,139,318 to Foser, for example, the entire content of which isincorporated herein by reference, describes a particularly useful colorkey for selecting a proper color for a dental restoration. The color keyincludes a number of detachable, tooth sample elements that are formedof the same materials and colored in the same manner, as the dentalrestoration. In addition, the tooth sample elements include a firstsurface having a texture and curvature that matches a natural tooth, anda second surface that is smooth and flat. The first surface provides thepossibility to test the impression the identically produced restorationwill have in the same location, while the second surface provides animproved evaluation of color only, as it can be positioned more easilywithin the patient's mouth for comparison with surrounding dentition.

Other, commercially available dental shade guides include, for example,Chromoscop™ (Ivoclar Vivadent, Inc., Schaan, LI); Vitapan Classical™(Vita-Lumin™ Vacuum Shade Guide) and Vitapan 3-D Master™ (Vident, Brea,Calif.); and Bioform™ and TruMatch™ (Dentsply International, Inc.,Milford, Del.).

Once the color of the prosthesis has been determined, an abutment havinga cuff that most similarly matches that color is used in the implantrestoration. Depending upon the dental shade guide system being used, aseries of colored abutments, specific for that system, would beavailable to choose from.

The principles of the present invention thus provide several advantagesover conventional dental implant restoration systems. The inventionsimplifies the restoration process, in that the fabrication of theprosthesis no longer has to take the color of the abutment intoconsideration. The abutment includes a cuff matching the color chosenfor the prosthesis. Therefore, the interface between the abutment andthe restoration is aesthetically enhanced and visually less detectable.In contrast, in accordance with the prior art, the color of therestoration was determined by the combination of the colors of theabutment and the prosthesis. Typically, the technician creating therestoration would obtain a standard abutment and then determine a colorfor the prosthesis that, when combined with the color of the abutment,would result in the desired color for the final restoration.

By utilizing an abutment having the same color as the prosthesis, thefinal restoration has a greater depth, providing a much more naturalappearance. Just as the “stump” of a damaged tooth provides anatural-colored framework for the reconstruction of the tooth, theabutment of the present invention provides a natural-colored frameworkfor the fabrication of a prosthesis.

In some instances, the restoration may include a layer of dental cementbetween the abutment and the prosthesis. Prior to the present invention,the practitioner would choose a cement having a color that wouldproperly combine with the colors of the abutment and the prosthesis, toobtain the desired color for the final restoration. With the presentinvention, however, because the abutment matches the color of theprosthesis, no additional determinations are required, and a clearcement may be used.

In a typical jawbone anchored dental restoration, after the implantsystem has been fixed within the patient's mouth, the gum is restoredaround the system, such that it extends above the lower surface of theprosthesis. With normal aging however, it is not uncommon that the gumline will recede, exposing the lower surface of the prosthesis, as wellas a portion of the abutment. With prior art abutments, this could causean unsightly, unnatural appearance. In accordance with the presentinvention, however, as the color of the prosthesis and the abutment cuffare matched, the appearance of the abutment is not noticeable even ifexposed, and the implant restoration blends naturally with thesurrounding dentition.

FIGS. 4 through 6 show another embodiment of an abutment 200 of thepresent invention. Abutment 200 is a monolithic or single-unitstructure, which can be anchored to an implant 202 shown in FIG. 7. Adental prosthesis, such as a crown 204 shown in FIG. 7, is positionedover abutment 200, which is connected to implant 202 with an attachmentscrew 206 through bore 207 in abutment 200. In such design, the abutmenthas a female connection component and the implant body has a maleconnection component. It should be mentioned that the means ofattachment of abutment 200 to an implant is not limited to an exterioranti-rotational connection as depicted in FIG. 3. Other modes andmethods of attachment may be used, including but not limited to,internal connection components. The abutments herein may be adapted toconnect to any type of implant.

Abutment 200 is a single-unit structure fabricated of a ceramicmaterial. As shown in FIGS. 4 through 7, abutment 200 combines the coreand cuff of the previous embodiments into a single unit, which isfabricated of a single piece of ceramic material. The base of theabutment includes a collar 208, having a planar bottom side 210 whichmay fit flush against an implant, such as implant 202. The upper side ofcollar 208 has a lip 212 that extends around the periphery of collar208. The coronal or top section 214 extends upwardly and is shapedsimilar to a tooth structure. A dental prosthesis, such as crown 204 inFIG. 7 fits upon lip 212 and atop upper section 214 of abutment 200.

Collar 208 is preferably gingival or pink-colored to match the gingivaltissue surrounding implant 202 in a patient's mouth. By shading collar208 with a pink or gingival-colored shade, the abutment will camouflagewith surrounding dentition and gingival tissue in the patient's mouth ifthe gingival tissue in the patient's mouth should recede.

The abutments described herein may be used as is, or it may be necessaryto alter and prepare the abutment to customize it to more precisely fita patient. As shown in FIGS. 4 and 5, lip 212 forms the originalcervical line of abutment 200. In preparing the abutment to better fitthe patient's mouth, it may be necessary to move the cervical line tocoincide with the cervical line in the patient's mouth, if gum tissuehas receded. In order to adjust the cervical line, collar 208 may befabricated of different colored layers of material. The inner core ofcollar 28 may be dentin-colored (to match the cervical area of thetooth) and the outer layer may be gingival-colored. The gingival-coloredlayer may vary in thickness from about 0.25 to about 1.00 mm Thetechnician may lower the cervical line as shown in FIGS. 4 and 5 byremoving the gingival-colored layer covering the area 213 from the pointof the original cervical line 212 to the new cervical line 215. Byremoving the gingival layer in area 215, the dentin-colored layered isrevealed and the cervical line is moved from line 212 to line 213. Theabutment is able to effectively camouflage with the patient's existingdentition and gingival tissue.

Upper or coronal section 214 is preferably divided into three regions,namely the cervical region 216, the central region 218 and the incisalregion 220, which will have different shades or color to simulate thenatural appearance of a tooth. These regions are mere approximations andvary from abutment to abutment, depending on the size, shape anddentition to which the abutment must correlate or match. Each regionwill have different requirements with regard to visual appearance. Thus,the appearance of lower or cervical region 216 of the abutment, whichmay vary from piece to piece, is preferably matched to the cervicalregion of the prosthesis and the cervical region of the surroundingdentition. The central region 218 of the abutment is preferably matchedto the central region of the prosthesis and central region of thesurrounding dentition. The incisal region 220 is preferably matched tothe incisal region of the prosthesis and the incisal region of thesurrounding dentition. Shade determination for the three coronal regionsmay be customized for the individual patient using one of thecommercially available dental shade guides, for example, Chromoscop™(Ivoclar Vivadent, Inc., Schaan, LI); Vitapan Classical™ (Vita-Lumin™Vacuum Shade Guide) and Vitapan 3-D Master™ (Vident, Brea, Calif.); andBioform™ and TruMatch™ (Dentsply International, Inc., Milford, Del.), orby using one of the commercially available intraoral spectrophotometers, for example, Easyshade (Vident, Brea, Calif.) and Shade Vision(X-Rite, Inc., Grand Rapids, Mich.). Accordingly, the natural toothcolor of the abutment will enhance the natural appearance of theprosthesis.

Reference is further made to FIGS. 8 through 10 which illustrate anabutment 300 showing an alternate form of attachment to an implant 302and crown 303. Abutment 300 includes a bore 304 which fits flush withthe conically-shaped top 306 of implant 302. Top 306 of implant 302 andbore 304 may vary in size, shape and/or design. It is preferable thatbore 304 is tapered. FIG. 9 is a facial view of abutment 300 and FIG. 10is a lateral view of abutment 300. FIGS. 11 and 12 show variations inthe shape of bore 304. FIG. 11 shows a conical-shaped bore with bevelededges 306. FIG. 12 shows a semispherical-shaped bore 308. As withabutment 200, abutment 300 is a single-unit structure fabricated of aceramic material.

FIGS. 13 and 14 show a close-up view of an alternate embodiment of thetop 310 of implant 302. Top 310 includes one or more chamfered sections312 which prevent rotation of abutment 300 on implant 302 when stress isapplied by the patient, for example, during chewing.

All the variations discussed above with respect to abutment 200 apply toabutment 300. The abutments herein may be customized in shape and colorto enhance the natural effects provided by the dental prosthesis. Bytaking measurements of the site of desired tooth replacement anddetermining the type of tooth to be replaced, a model of an abutment canbe selected from the inventory and/or customized to the proper shape andcolor to fit naturally with the patient's existing dentition.

As with abutment 104 having core section 120 and cuff 140, allconfigurations and anatomical variations discussed above are applicableto single-unit abutments 200 and 300, which combine the core and cuffinto one monolithic unit.

The abutments may be shaded during manufacturing by coating oxide powderwith one or more coloring substances to produce a colored powder,pressing the colored powder to produce a shaped body and sintering thecompressed shaped body. Reference is made to commonly owned co-pendingU.S. Patent Application Publication No. 20070292597 which discloses amethod of making zirconia multi-colored blanks and products thereof,U.S. Pat. No. 6,379,593, which discloses a method of making amulti-colored ceramic body, and U.S. Pat. No. 4,970,032, which discloseslayered blanks for milling dental materials, all of which are herebyincorporated by reference in their entirety. It is also possible tofabricate partially or fully sintered blanks, which can be furthermilled into the desired abutment shape.

Alternatively, the abutment may be fabricated of a ceramic materialwhich has been partially or fully sintered and thereafter shaded bystaining the partially or fully sintered abutment with stains to matchthe prosthesis, surrounding tooth surface and surrounding gingivaltissue.

It is preferable that the ceramic material is a high strength ceramicmaterial such as zirconia, alumina, and mixtures thereof whereby theflexural strength is greater than about 1000 MPa, more preferablygreater than about 1500 MPa, and most preferably greater than about 2000MPa. Some applicable materials are known in the art as yttria orceria-stabilized tetragonal zirconia (Y-TZP and Ce-TZP), zirconiatoughened alumina (ZTA), alumina-toughened zirconia (ATZ), mixturesthereof, composites thereof and functionally graded composites thereof.The flexural strength of these materials customarily exceeds 1000 MPawith better ones exceeding 1500 MPa and even 2000 MPa. Examples ofmaterials useful herein include, but are not limited to, ZirCAD™ blocksfrom Ivoclar Vivadent, nanoZir™ zirconia from Hint-ELs and Ziraldent™material from Metoxit AG.

In addition to the abutment being anatomically shaded as described aboveto simulate natural dentition and to further match the surroundingdentition and gingival tissue in a patient's mouth, the abutment mayalso be anatomically shaped to match the shape of the surroundingdentition, gingival tissue and prosthesis which is positioned thereon.It is most preferable that abutment 200 has a shape that is near the nettooth shape of the prosthesis to which it will be attached and a shadethat is anatomically shaded to match natural dentition such that thecolor and translucency distribution characteristics simulate naturaldentition. The anatomically shaded multicolor abutment mimics the colorand translucency distribution in natural teeth in such a way that acrown, positioned on the abutment, will require no or very littleveneering porcelain to mimic the replaced tooth. The near net shape andshade of the abutment obviates the need to use a thick crown over theabutment, improving the overall strength and structural integrity of theimplant system without compromising aesthetics. Since more strength isprovided by the abutment, less strength is needed in the crown orveneering layer (porcelain or composite), which sits atop the abutment.The esthetic contribution of the veneering layer becomes, if not lessimportant, at least more consistent and predictable. As the abutmentgets closer to the net shape and becomes more naturally shaded, itobviates the need for a restoration on top, and it becomes therestoration itself. In addition to the materials mentioned above, thenet shaped abutment may be fabricated of lithium disilicate withflexural strength exceeding 600 MPa, as disclosed in commonly owned,copending U.S. Patent Application Publication No. 20070042889, which ishereby incorporated by reference in its entirety.

In selecting the correct shades for the abutment, the color components,hue, chroma and value, are evaluated,. Hue is the dimension of colorthat enables us to distinguish one family of color from another; chromadefines the relative intensity of a particular color, i.e., the moreintense a color is, the higher its chroma level; and value describes therelative whiteness or blackness of a particular color, i.e., thebrighter the color, the higher its value. In addition to thesecomponents, characteristics such as opacity, fluorescence, andtranslucency may also be considered during the determination of thecorrect shades for the abutment.

A finished dental restoration should match the color of the patient'steeth, i.e., it should be “tooth colored”. The colors of human teethappear to range from a light, almost white-tan to a light brown, andoccupy a very specific color space. This color space can be described bythe commonly used CIE (Commission Internationale de l'Eclariage) L*, a*,b* conventions, which represents colors in a three-dimensional Cartesiancoordinate system. L*, or “value”, is a measure of luminance orlightness, and is represented on the vertical axis (black is 0 and whiteis 100). The a*, b* coordinates, are a measure of chromaticity and arerepresented on the horizontal coordinates, with positive a* representingred and negative a* representing green, and positive b* representingyellow and negative b* representing blue. U.S. Pat. No. 6,030,209, whichis incorporated herein by reference, presents the CIE L*, a*, b* colorcoordinates of tooth colors represented by the Vita Lumen® shade guidesystem manufactured by Vita Zahnfabrik (i.e., it presents the colorspace of tooth colors). Herein, “tooth color” is taken to mean CIE L*,a*, b* color coordinates that fall within, or very close to, this colorspace.

In the fabrication of the abutment herein, the ranges of the L*a*b*values are set forth in Table 1 below along with the amount of opacitypreferred.

TABLE 1 Range L* a* b* Opacity (CR) % Min 27.00 −17.00 −29.00 5.00 Max96.00 +28.00 +52.00 99.00

The values will vary in the abutment, depending on the area to beshaded. Table 2 sets forth ranges for the gingival, cervical, central(matched to dentin) and incisal regions.

TABLE 2 Abutment Areas L* a* b* Gingival 40-75 12-25   6-20 Cervical70-90 −2-+10 12-36 Dentin 60-80 −3-+10 12-36 Incisal 50-75 −1 + 10 −1 +30

The single-unit abutment is facile and effective way to provide anatural-looking prosthesis. The gingival-colored base section of theabutment is able to camouflage with the surrounding gingival tissue andthe coronal section enhances the natural look of the prosthesis.

EXAMPLE

Adequate alveolar bone must first be present at an edentulous site inorder to properly treat a patient with a dental implant. After thesecure placement of the dental implant in the patient's jawbone, anappropriate abutment type is selected that will provide support for thefinal restoration. Where the final restoration being considered is anall-ceramic restoration, selection of an implant abutment according tothe present invention, that is color-shaded similar to natural teeth issuggested, as opposed to a metallic abutment which may shadow throughthe ceramic prosthesis and affect the color of the all-ceramicrestoration. An impression and shade is taken using one of the knownshade guide systems and sent to the laboratory for fabrication of thefinal restoration. The color of the abutment is matched to the chosencolor for the restoration. The final restoration is then fit within thepatient's mouth and permanently mounted.

Although preferred embodiments have been depicted and described indetail herein, it will be apparent to those skilled in the relevant artthat various modifications, additions, substitutions, and the like canbe made without departing from the spirit of the invention and these aretherefore considered to be within the scope of the invention as definedin the claims which follow.

What is claimed is:
 1. A dental implant abutment comprising: amonolithic single unit structure having a basal end for anchoring to animplant and a coronal end for supporting a dental prosthesis, whereinthe basal end and coronal end meet at a cervical line; wherein themonolithic single unit structure is fabricated of lithium disilicate;wherein the monolithic single unit structure is multicolored throughoutto match the color of the dental prosthesis, the surrounding dentitionand the surrounding gingival tissue; wherein the basal end comprises acollar having a lower side and an upper side, the upper side of thecollar forming the cervical line, the collar further comprising a coreand an outer layer of material overlaying the core, wherein the core isa dentin color; wherein the outer layer is a gingival color, and whereinthe cervical line may be lowered by removing the outer layer ofmaterial; and wherein the lithium disilicate has a flexural strengthexceeding 600 MPa.
 2. The dental implant abutment of claim 1 wherein themulticolored single unit structure varies in shade, translucency,opacity, opalescence, and fluorescence from the basal end to the coronalend.
 3. The dental implant abutment of claim 2 wherein the basal end isgingival pink-colored, the coronal end is incisal-colored and the areain between the basal and coronal ends is dentin colored.
 4. The dentalimplant abutment of claim 3 wherein the dentin-colored area includes acervical-colored area where the basal end meets the coronal end.
 5. Theimplant abutment of claim 2 wherein the shade is measured by CIE L*, a*,and b* color coordinates and wherein the CIE L*, a*, and b* colorcoordinates are within the CIE L*, a*, and b* color space regionassociated with tooth colors and translucencies.
 6. The dental implantabutment of claim 5 wherein value L* ranges from about 27 to about 96,value a* ranges from about −17 to about +28, value b* ranges from about−29 to about +52 and the contrast ratio (CR) ranges from about 5 toabout 99%.
 7. The dental implant abutment of claim 1 wherein the lithiumdisilicate has a flexural strength exceeding 700 MPa.
 8. The dentalimplant abutment of claim 1 wherein the lithium disilicate has aflexural strength exceeding 800 MPa.
 9. The dental implant abutment ofclaim 1 wherein the lithium disilicate has a flexural strength exceeding900 MPa.
 10. The dental implant abutment of claim 1 wherein themonolithic single unit structure is anatomically shaped and shaded. 11.The dental implant abutment of claim 1 wherein the outer layer ofmaterial has a thickness in the range from about 0.25 to about 1.00 mm.12. The dental implant abutment of claim 1 wherein the location of thecervical line changes after the abutment is prepared for placement on animplant.
 13. The dental implant abutment of claim 12 wherein theabutment is prepared using hand-held instruments and procedures,partially automated instruments and procedures, or fully automatedinstruments and procedures.
 14. A dental implant restoration systemcomprising: an implant; an abutment fixed to an implant; and a dentalprosthesis disposed atop the abutment; wherein the abutment comprises amonolithic, single-unit structure having a basal end for anchoring to animplant and a coronal end for supporting a dental prosthesis, whereinthe basal end and coronal end meet at a cervical line; wherein themonolithic single unit structure is fabricated of lithium disilicate;wherein the monolithic single unit structure is multicolored throughoutto match the color of the dental prosthesis, the surrounding dentitionand the surrounding gingival tissue; wherein the basal end comprises acollar having a lower side and an upper side, the upper side of thecollar forming the cervical line, the collar further comprising a coreand an outer layer of material overlaying the core, wherein the core isa dentin color; wherein the outer layer is a gingival color, and whereinthe cervical line may be lowered by removing the outer layer ofmaterial; and wherein the lithium disilicate has a flexural strengthexceeding 600 MPa.
 15. The dental implant restoration system of claim 14wherein the abutment is attached to the implant externally by a screw orinternally by a bore contained in the abutment.
 16. The dental implantrestoration system of claim 14 wherein the implant comprises a maleconnection component and the abutment comprises a female connectioncomponent to connect to one another.
 17. The dental implant restorationsystem of claim 14 wherein the implant comprises a female connectioncomponent and the abutment comprises a male connection component toconnect to one another.
 18. The dental implant restoration system ofclaim 14 wherein the basal end is gingival pink-colored, the coronal endis incisal-colored and the area in between the basal and coronal ends isdentin colored.
 19. The dental implant restoration system of claim 14wherein the lithium disilicate has a flexural strength exceeding 700MPa.
 20. The dental implant restoration system of claim 4 wherein thelithium disilicate has a flexural strength exceeding 800 MPa.
 21. Thedental implant restoration system of claim 4 wherein the lithiumdisilicate has a flexural strength exceeding 900 MPa.
 22. The dentalimplant restoration system of claim 14 wherein the outer layer ofmaterial has a thickness in the range from about 0.25 to about 1.00 mm.23. The dental implant restoration system of claim 14 wherein thelocation of the cervical line changes after the abutment is prepared forplacement on an implant.
 24. The implant restoration system of claim 23wherein the abutment is prepared using hand-held instruments andprocedures, partially automated instruments and procedures, or fullyautomated instruments and procedures.
 25. The dental implant restorationsystem of claim 14 wherein the dental prosthesis comprises dentalceramic, porcelain, composite or hybrid material.
 26. The dental implantrestoration system of claim 25 wherein the dental ceramic, porcelain,composite or hybrid material is fabricated using hand-held instrumentsand procedures, partially automated instruments and procedures, or fullyautomated instruments and procedures.
 27. The dental implant restorationsystem of claim 26 wherein the partially or fully automated instrumentsand procedures comprises CAD/CAM, Rapid-Prototyping, plasma or flamedeposition, electroforming, spraying or dipping.
 28. A dental implantrestoration system comprising: an implant; and an anatomically shapedand shaded abutment fixed to the implant; wherein the anatomicallyshaped and shaded abutment comprises a near net-shape monolithic,single-unit structure having a basal end for anchoring to an implant anda coronal end approximating the shape of a dental prosthesis, whereinthe basal end and coronal end meet at a cervical line; wherein themonolithic single-unit structure is fabricated of lithium disilicate;wherein the monolithic single-unit structure is multicolored throughoutto match the color of the dental prosthesis, the surrounding dentitionand the surrounding gingival tissue; wherein the basal end comprises acollar having a lower side and an upper side, the upper side of thecollar forming the cervical line, the collar further comprising a coreand an outer layer of material overlaying the core, wherein the core isa dentin color and wherein the outer layer is a gingival color, andwherein the cervical line may be lowered by removing the outer layer ofmaterial; wherein the lithium disilicate has a flexural strengthexceeding 600 MPa.
 29. The dental implant restoration system of claim 28wherein the outer layer of material has a thickness in the range fromabout 0.25 to about 1.00 mm.
 30. The dental implant restoration systemof claim 28 wherein the location of the cervical line changes after theabutment is prepared for placement on an implant.
 31. The implantrestoration system of claim 30 wherein the abutment is prepared and/orfinished using hand-held instruments and procedures, partially automatedinstruments and procedures, or fully automated instruments andprocedures.
 32. The dental implant restoration system of claim 28further comprising an aesthetic layer.
 33. The dental implantrestoration system of claim 31 wherein the finishing the abutmentcomprises cutting-back and layering.
 34. The dental implant restorationsystem of claim 31 wherein finishing the abutment comprises staining andglazing.
 35. The dental implant restoration system of claim 28 whereinthe abutment requires no aesthetic layer prior to placement onto thedental implant in the patient's mouth.
 36. The dental implantrestoration system of claim 32 wherein the aesthetic layer is aveneering material comprising dental ceramic, porcelain, composite orhybrid material.
 37. The dental implant restoration system of claim 36wherein the dental ceramic, porcelain, composite or hybrid material isfabricated using hand-held instruments and procedures, partiallyautomated instruments and procedures, or fully automated instruments andprocedures.
 38. The dental implant restoration system of claim 37wherein the partially or fully automated instruments and procedurescomprises CAD/CAM, Rapid-Prototyping, plasma or flame deposition,electroforming, spraying or dipping.
 39. The dental implant restorationsystem of claim 28 wherein the lithium disilicate has a flexuralstrength exceeding 700 MPa.
 40. The dental implant restoration system ofclaim 28 wherein the lithium disilicate has a flexural strengthexceeding 800 MPa.
 41. The dental implant restoration system of claim 28wherein the lithium disilicate has a flexural strength exceeding 900MPa.